REWE International AG: CO2 in deep freezing standard but not envisaged for medium temperature cooling yet

By Sabine Lobnig, Jul 13, 2012, 16:28 5 minute reading

REWE International AG - the Austrian daughter company of the German REWE Group - is introducing the eco-store concept with CO2 cascade systems. In smaller sized stores, additional investment costs are between 8,000-15,000 euros, in larger cash & carry markets the price has equaled out with traditional installations. As REWE has committed to reduce carbon emissions by 30% by 2015, emissions from refrigeration are an important factor. In the mid-term view, REWE considers CO2

The municipality of Perchtoldsdorf, near Vienna, Austria, hosts BILLA’s latest eco-store. BILLA is the brand name of REWE group's mid-sized supermarkets in Austria. This new BILLA eco-store costs 2.6 million euro and features the latest green technologies, including a 90kW CO2/R134A cascade system that uses heat rejection from the deep freezing cycle in the normal cooling to keep the pressures in the subcritical range, which in turn helps keep the price premium as compared to conventional systems down. In the normal cooling range the system uses R134a with the potential of being replaced with XP10 in the future.

Price premium for CO2 systems decreasing

The price premium for CO2 cascade systems depends strongly on the store size. For BILLA markets which on average are about 600 square meters, it amounts currently to around 15,000 euro per system, however with a decreasing trend. In bigger markets, the price premium is less because the pipe dimensions allow for economies of scale. R744 needs in the suction line almost only half the diameter as compared to conventional systems, which considering the price of copper allows for substantial savings. The CO2 cascade systems for REWE's MERKUR markets cost only around 8,000 euro more than would conventional systems. In the case of even bigger markets such as REWE's cash & carry markets AGM, prices have already leveled out.

No energy efficiencies with CO2 so far but environmental benefit

The motivation of REWE International AG to introduce CO2 in deep freezing is solely based on environmental considerations. The company does not expect energy efficiencies with the CO2 systems. However, the REWE Group has introduced a sustainability programme in 2008 and strives to reduce direct and indirect CO2 emissions by 30% until 2015.

“In this context, the refrigerant emissions are an important factor and the introduction of CO2 as refrigerant will make a valuable contribution to reach our 2015 target,” says Peter Breuss, technical director of REWE International AG.

In the mid-term view, REWE International AG considers CO2 cascade system as the best solution available on the market.

CO2 in the normal cooling

“In the normal cooling, CO2 transcritical systems are not yet up to bar,” says Thomas Pöll, technical expert of REWE International AG in Austria. “Because of their lesser energy efficiency, overall CO2 emissions would be worse, seen the increased electricity consumption. Therefore CO2 in normal cooling is currently not an option for us.”

“We monitor new developments in the refrigeration market of course closely, and we are certainly open to revise our strategy should there be available by 2015 or 2018 CO2 transcritical systems that have the same or only slightly higher energy consumption than conventional system. Currently, however, the feasibility of this has not yet been demonstrated clearly,” says Peter Breuss.

Safety first but not enough trained refrigeration experts

Smaller rooms like single cooling cells and cold rooms are equipped with CO2 sensors, while the lager rooms like the storage halls are vast enough to prevent any concentration of CO2 that could be harmful to the employees, seen that the system only contains 45kg of CO2 in the deep freezing and 120kg of R134a in the normal cooling

Important for REWE International AG is also to have the necessary workforce to maintain and service the CO2 systems. For the moment, there are not enough technicians experienced with CO2 as refrigerant. For this reason, REWE International AG always tries to build first at least one pilot with the relevant supplier to collect experience in-house and together with the supplier.

The first CO2 cascade system had been introduced as pilot in 2008 in a BILLA store in Sinabelkirchen. The second store has now been opened in Perchtoldsdorf, with the aim to have for BILLA around 10 CO2 pilot stores to test in every region with every of the supplying companies in at least one store.

For the lager markets like AGM and MERKUR, the CO2 cascade system has become standard and is implemented in all new markets, the largest one being so far in place in the cash & carry market AGM in Wr. Neustadt.

The aim is to reduce energy consumption by 50% as compared to conventional BILLA stores

BILLA’s eco-store in Perchtoldsdorf is Austria's first supermarket having achieved the klima:active standard, introduced by the Austrian Ministry of Life in the framework of an action plan for active climate protection as well as having received gold certification for sustainable building by ÖGNI and ÖGNB (~ equivalent to the US LEED or the UK Breeam). The eco-store was developed in combination with a public park deck and financed in a private public partnership with the municipality of Perchtoldsdorf.

REWE Group Germany: Award at Rio +20 for REWE Green Building concept with CO2 transcritical

Meanwhile, the "REWE Green Building - Concept Future" of Rewe Group Germany – the parent company of REWE International AG in Austria - has been awarded at Rio +20 as one of the most sustainable concepts. The Green Building concept has been implemented in 2009 in a carbon-neutral supermarket in Berlin. The Green Building pilot store was the first super- market in the world to receive the Sustainable Building Certificate in Gold from the German Sustainable Building Council. A host of energy-savings measures deliver almost 50% savings compared to a standard REWE supermarket. The store is flooded with daylight; brightness sensors ensure that artificial lights turn on only when needed. Rooftop photovoltaic panels generate almost one-third of the electricity consumed by the store. A ground source heat pump maintains an ideal temperature in the supermarket in summer and winter. Harvested rainwater is used to clean the floors, flush toilets, and water the building’s grounds. The refrigeration system furthermore uses exclusively natural refrigerants, namely CO2 in deep freezing and normal cooling as well as propane in plug-in cabinets.


By Sabine Lobnig

Jul 13, 2012, 16:28

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